High capacity air jet chaffer

ABSTRACT

A crop chaffer for combines features air jets which deliver an air blast to the grain and chaff. The air jets and sifting screens are arranged in a cross sectionally “stair step” pattern in which the tread of each stair is the screen and the riser of the each stair has the air jet located thereon. The air jets do not allow grain passage, while the apertures in the screens do not produce a strong current of air. The chaffer is divided into individually separable and replaceable elements, thus greatly easing the burden of changing chaffers in the combine.

CROSS REFERENCE TO RELATED APPLICATION

The application claims the priority and benefit of U.S. patentapplication Ser. No. 10/057,615 filed Jan. 25, 2002, which has beenallowed, in the name of the same inventor, Marvin James Gorden, andentitled HIGH CAPACITY AIR JET CHAFFER, the specification of which ishereby incorporated by reference.

This application contains no new matter relative to the originally filedapplication identified above. The following changes have been made inthe specification on this page only. This CROSS REFERENCE is added. TheFIELD OF THE INVENTION has been very slightly modified.

FIELD OF THE INVENTION

This invention relates to generally to agricultural combine use andspecifically to an improved chaffing/sieving element.

The CLAIMS presented are taken from the claims 12 through 15 of theoriginally filed application identified above. A copy of the DECLARATIONof the originally filed (parent) application identified above isincluded under the provisions of MPEP Sec. 602.05(a).

BACKGROUND OF THE INVENTION

Agricultural combines are widely available machines which enormouslyspeed the processes of harvesting, threshing and cleaning of all typesof grains. By minimizing the labor required for harvesting, combineshave contributed to the dramatic increase in availability and decreasein price of grains.

The combine machine traverses the field of grain in swathes which coverthe area of the ripened crop. As it travels, the combine brings graininto its forward end and feeds it to a separating apparatus or thresherwhich threshes the grain, separating grain and grain heads from stalks,straw, dirt and other undesirable materials. An example of an axial flowrotor for threshing of the grain may be seen in U.S. Pat. No. 5,125,871,issued Jun. 30, 1992, to the same inventor as the present application.The present invention concerns the succeeding processing stage: thechaffing of the grain.

After passing through the threshing stage, the grain is theoreticallyperfectly threshed. In reality, however, while the separating apparatusis efficient, some chaff, unthreshed grain, other materials, stems,and/or straw remains intermixed with the grain and further steps ofthreshing, separating and cleaning are normally required.

The cleaning section of a conventional combine is located to receivegrain and other material expelled from the separating apparatus. Atypical cleaning section includes a chaffer and a sieve mounted so as tomove back and forth reciprocally and a fan which produces a flow of airdirected through the sieve and chaffer. The sieve is usually mountedbelow the chaffer, although it important to note that some combines haveseveral layers of sieves and chaffers, or several in sequence. Intheory, the chaffer blows the chaff and other “materials other thangrain” (“MOG”) out of the stream of grain before the sieve sifts it.Reciprocation of the chaffer and sieve facilitates arrangement of thegrain and other materials into a crop layer or mat on top of thechaffer. Separation of the crop material is largely facilitated by theair from the fan flowing upwardly through the passages between thelouvered sieve and chaffer. Prior art chaffers/sieves include a seriesof adjacent louvers. A series of transverse elongated openings orpassages are defined between the adjacent louvers to grade the materialby density and size. Smaller, denser kernels of grain are allowed tofall through the openings despite the airflow upwards therefrom, afterwhich they fall through the sieve mounted below the chaffer, whereaslarger pieces of materials are blown or vibrated rearward in the airflowand off of the chaffer and sieve. The light material blown off thechaffer is discharged from the combine entirely, while heavierunthreshed heads of the crop still having grain is too heavy to blow andthus is moved off of the rear of the sieve, from where it is returned bythe tailings system to the separating apparatus for rethreshing.Finally, there is larger MOG which is carried over the end of thechaffer and falls or blows away from there.

Thus four categories of material are created: first, the grain, whichfalls through the chaffer/sieve for storage, second unthreshed materialwhich is sent back for rethreshing, and third chaff, which is blownentirely clear. Fourth, the larger material other than grain is carriedoff the end of the rethreshing louvers of the chaffer. To allow use of asingle chaffer for grain crops of different sizes, the louvers may beadjusted in rotation, thus altering the spacing between the louvers andthe characteristics of the air-flow/air-blast through them.

The proper opening between the louvers is necessary for efficientoperation of the combine's chaffer. If the openings are too large, strawand other material ends up falling between them with the grain,contaminating the grain. On the other hand, if the louvers are adjustedto have openings which are too small, the individual grain requires alonger average time before finding a hole of sufficient size to passthrough, thus causing a buildup of the grain, thus causing anunpredictable diminishment of the air flow, thus reducing both the speedand the efficiency of operation. Worse, some of the grain is carried offthe back of the chaffer and if it falls through the louvers, is returnedto the thresher unnecessarily, resulting in an excessive percentage ofthe grain being cracked, or if it is carried over the louvers ends upfalling out the back of the combine and being lost. If the louvers arenot evenly adjusted the grain may not receive uniform treatment, and insome areas, the MOG may fall through the chaffer while in others, evengrain is blown away.

One particular issue is that the husk surrounding the grain may clingtightly to the grain, especially in a wheat crop, resulting in “whitecaps”: kernels slightly larger than the norm having husk still attached.Adjusting chaffers to use only size in a sifting or filtering apparatusto successfully reject the white caps while accepting the only slightlysmaller grains which are fully threshed is a difficult process. The sizedifference between the chaffed and unchaffed grains can be minute: inwheat, the size difference may be as small as {fraction (5/1000)} of aninch.

An example of prior art that shows a commonly used louvered system isU.S. Pat. No. 4,511,466, issued Apr. 16, 1985 to Jones et al for“Chaffer Slat”. This clearly shows that the grain flow must make a turnin flow direction in order to advance to the clean grain collectionsystem, this turn may be anywhere from 90 degrees to almost 180 degrees,depending upon circumstances. The grain density is greater than that ofthe chaff, and the grain has more inertia than does the chaff, and thisinertia must be overcome in making the turn. Also, in order for thegrain to fall through a louver chaffer it must rely on gravity to dropbetween the louvers and penetrate the blast of air passing in the exactopposite direction. As can be easily appreciated there is a conflict atthis point: a powerful blast of air is needed to float the chaff abovethe chaffer and out the back end of the combine, but the blast must notbe so strong as to prevent the grain (which is being driven backwardsacross the chaffer) from making its turn and falling against that airblast through the louvers to the clean grain collection system. It isalso worth noting that while the grain flow path pictured in FIG. 1 ofthe '466 patent is depicted to closely follow the underside of eachlouver, in fact gravity and the reciprocating motion of the chaffercauses the grain to actually land upon the top side of the followinglouver. However, this contact with the topside of the following louversupports the grain and diminishes the effect of gravity in moving thegrain downwards against the blast of air. In addition, the MOG tends tocomprise a mixture which may include straight stalks of various lengths.With large numbers of such stalks continuously fluttering and twirlingin the air blast, it is inevitable that some number of them randomly endup aligned parallel to the air blast. They can then fall with great easestraight into the air blast. The slats pictured by the '466 patent areunlikely to catch and filter out such stalks as the slats are themselvesaligned parallel to the airflow, and thus a certain percentage of stalkscan simply fall straight through the chaffer to contaminate the grain.One final problem with such devices is that the reciprocating motion ofthe chaffer/sieve combination tends to “stuff” the lighter, less inertiadriven material, (chaff, and other materials other than grain) into theslanted louver openings, contributing to the problem of fouling of thechaffer/sieve.

In such a louver or air foil chaffer system reliance for filtration ison the size of the openings, but in any given crop, the grain varies insize by as much as 100%. The openings of chaffers and sieves must be setwide enough to allow the largest individual grains of the crop to passthrough. The opening is then wider than necessary for the smaller grainsof the same crop. Any of the smaller grains that have attached husks(“white caps”) will pass through and contaminate the clean grain in thecollection system. However, it is obvious that as the louvers areadjusted, the angle of the air blast is altered, the speed of the airblast is changed, the amount of support offered to the grains as theyslide down the louvers is altered, and numerous other changes occur.

To illustrate the complexity of the mechanics involved, consider thecase in which the louvers are narrowed from a fairly wide openconfiguration which was previously selected to allow a relatively largegrained crop to pass there through. The narrowing of the louvers doesallow them to function as screens or filters for a smaller size of crop.However, the smaller openings result in an air blast which ispotentially more powerful, despite the fact that a smaller and lightergrain must now fight it's way downwards against this blast. The louvers'relatively flat angle means that the louver's top surfaces offer to thesmaller grains a greater degree of support, thus reducing the pull ofgravity to overcome the air blast. The fan speed must thus be adjustedto attempt to compensate not only for the smaller crop but also for theunpredictable effects of the louvers on that crop. And the new lowerangle of the air blast will tend to move the mat of grain and chaffbackwards faster.

In systems commercially available, the construction of the chaffer isextremely light: thin metal louvers, supports of light construction, andmoving parts having fairly generous tolerances. In addition linkagesnecessary to actuate the multiple slats must run from the back of thechaffer (where the operator may have access) to the front. The combinedeffect is to produce an uncertain control response. The loose linkages,multiplied over the length of the chaffer, may result in the louveradjustment at the front end being very different from the louveradjustment at the back end, where the operator can easily see it.Individual slats may be warped by fatigue or bent by MOG falling ontothem from the separator. In some commercially available systems, thelength of the chaffer is divided up into multiple zones, each having aseparate control system, in an attempt to deal with these problems.

The sieve below the chaffer also has unpredictable effects on thechaffer's efficiency and capacity. When filtering small seeds the angleof the louver is set as low as possible to allow the small seeds to passinto the clean grain collection system and prevent even slightly largermaterial other than grain from contaminating the collected clean grain.But the resulting restriction by the sieve of the air flow upwards tothe chaffer starves the chaffer of needed air to function at a highcapacity. To prevent overloading of the air starved chaffer, theoperator must in turn slow the ground speed of the combine (thusdecreasing the intake rate of the crop) or increase the speed of thecleaning fan to supply adequate air to the chaffer. Failure to do eitherwill result in an overload condition on the top of the chaffer as isplugs with a mat of crop material. But increasing the fan speed, asdiscussed elsewhere, results in an undesirable loss of grain and alsoundesirable rethreshing of grain. Reducing ground speed and the rate ofcrop intake means that harvesting requires more time, which not onlyincreases grain production cost but increases the chance thatintervening events (time and weather, for example) may cause loss of aportion of the crop.

The reciprocating motion of the chaffer will also tend to move the matof crop material (chaff, straw, stalks, and a percentage of grain) atopthe chaffer rearwards out the discharge of the combine and wastewhatever grain is mixed into the mat. If the operator attempts toprevent chaffer overload by increasing the fan output instead ofreducing the ground speed of the combine, the sieve is over-driven withair and the grain is hit with a blast of air strong enough to blow intothe tailings return auger and is needlessly rethreshed. As mentionedelsewhere, rethreshing of clean grain results in cracking and adds tothe incoming crop from the harvester. When high levels of clean grain isreturned to the thresher the ground speed of the combine must be reducedto prevent overload of the separator.

Other examples of such prior art combine chaffers include U.S. Pat. No.5,041,059 issued on Aug. 20, 1991, to Ricketts et al, for “CleaningSystem for a Combine” and U.S. Pat. No. 6,053,812 issued on Apr. 25,2000, to Loewen et al for “Sieve Construction for a Combine Harvester”.In the '059 patent, a series of openings 88 are designed to allow grainto fall through louvers 62. However, since the louvers 62 have a gapbetween them, “allowing clean grain to fall through the sieve” (column7, lines 14,15), materials larger than openings 88 may penetrate thechaffer of the '059 reference. Having gaps wich allow the “clean grain”to fall through the “sieve” (the chaffer, despite the difference innaming convention) is both a drawback of the '059 patent and adistinction between that patent and the present invention.

A reference of interest is U.S. Pat. No. 5,176,574, issued on Jan. 5,1993 to Matousek et al for “Combine Cleaning System”. In the '574patent, numerous one dimensional jets or passages in an “air foil”section of the chaffer themselves function as the holes of a screen. Asshown in FIG. 5 (the representative diagram), the jets 88 are aligned inparallel rows. However, as stated in column 3, lines 7-9, and otherplaces in the reference, the passages provide granular sizing or sortingcapability. While it appears at first glance of FIG. 1 that there is aseparate sieve section aft of the air foil section, FIG. 2 shows thatthe section extending rearwards of the air foil section is used forlarger materials which are being sent back for rethreshing: this sectionof the chaffer overhangs return auger 52, which structure returnsunthreshed materials to the threshing stage. This same point is made incolumn 3, lines 42-47, “ . . . materials passing through the slatsection get recirculated to the threshing apparatus.” It is worthcommenting that if the “airfoils” of this reference were to beinterspersed among the slats, or vice-versa, the larger materials suchas chaff, white caps or unthreshed heads of the grain plants, allrequiring rethreshing, would not get rethreshed and would instead getmixed with the cleaned grain. It is also worth commenting that both theair foil/sieve holes and the gaps between the slats are located on theforward side of the troughs in which the airfoils sit, and that theairfoil openings 88 would continue to function as a sieve themselves nomatter how the '574 reference is rearranged, as that structure andpurpose is repeatedly taught in the reference, as pointed out above.

In general, the goals of combine chaffer designs are to first, allow ahigh capacity chaffing rate, that is to allow a high flow rate ofpartially threshed materials into and through the chaffer. This is ofimportance because the chaffing rate tends to be limiting factor incombine operation speed: increasing the chaffing capacity rate allows animmediate increase in combine operation. Second the chaffer must workefficiently to separate the grain from the chaff. High capacity ofoperations means little if the market quality of the grain is degradedsubstantially by the presence of excess chaff. These two goals mayconflict.

In functional terms, turning up the air blast allows faster operation ofthe chaffer, up to that point when the air blast merely causes grain tobe blown out the back of the combine with the chaff. This in turn leadsto the observation that two separate operations are occurring in thechaffer: one operation is that grain is being separated, allowed to fallthrough the sieve, and collected. The other operation is that chaff isbeing blown backwards over the sieve and eventually out the back of thecombine. (A third operation, alluded to earlier, is that unthreshedheads of grain are being collected for rethreshing.)

Another more practical problem with known chaffer designs is that ofaccess to the chaffers and/or sieves, as well as adjustment,replacement, and cleaning. The combine has evolved into a complexmachine with attachments such as grain loss monitors, chaff spreadersand straw choppers located at or near the discharge opening of thecombine. These extra attachments make access to the chaffer difficultand requiring extensive time consuming disassembly to remove the chafferand sieve. Thus whenever the chaffer must be changed, cleaned, adjustedor for any other routine maintenance, a good deal of effort is involved.In fact, the chaffer is normally only accessed from the rear, and theweight of any material clogging the chaffer, plus the weight of thechaffer and frame, plus the fact of access to one end only, all conspireto make pulling or adjusting the chaffer/sieve a tedious and difficulttwo person operation.

SUMMARY OF THE INVENTION

The present invention uses a series of substantially-uninterruptedprecision lateral horizontal air jets that focus the air blast, suppliedby the cleaning fan, into a thin, high velocity layer of air whichapproximately parallels the faces of the screens, rather than beingprimarily emitted from the orifices of the screens.

It is one feature of the invention that the air blast is directed abovethe screens, and so in addition to not passing through the screens alsodoes not pass directly across the face of the screens.

In another embodiment of the invention, the faces of the screens aredivided into a series of steps or troughs, in which the riser of eachstep (which riser may also be regarded as the front side of each trough)has at least one of the series of lateral horizontal airjets. Grainsupplied to the first riser is pushed rearward by the face of the riserand by the thin layer of high velocity air streaming through the airjet. The effect of gravity causes the grain to penetrate the thin airstream and fall on the screen of one of the step/troughs. The angle ofthe screen faces the approaching grain and is selected so as to favorgrain penetration. The grain on the screen is normally entirely belowthe thin high velocity air blast. As the screen is not the source of theair blast the grain is able to enter the openings of the screen withoutever directly facing a strong air blast.

It is thus one additional aspect of the present invention that the graindoes not have to reverse direction as it must in the louver or air foilchaffer/sieve designs. Since the grain does not have to fall directlyagainst the air blast, the fan speed can be increased without blowingthe grain out with the chaff or into the tailings return system.

It is another aspect of the present invention that as the fan increasesin speed, back pressure is created inside the plenum (the area beneaththe air jet chaffer). The back pressure causes air to rise through thescreens. However since the screens are fixed at an angle parallel to airstreaming from the cleaning fan directly toward the air jets, and sincethe holes in the screens are not designed as air jets, the airexhausting through the screen holes is at a much lower velocity thanthat from the air jets. The velocity of the air exhausting through thescreen holes is sufficient to prevent chaff and other light materialsuch as dust from entering the clean grain collection system. Such lightmaterial will be driven by vibration and air flow over the next riserand as it falls to the next trough/step, it will pass the next air jetand be lofted away from the screens.

It is a further feature of the present invention that any grain thatbounces off the surfaces between the screen holes moves by inertiarearward to the next riser and thus the next series screen holes, untilit penetrates a screen hole.

It is a further feature of the present invention that the air blast neednot be powerful enough to drive grain substantially rearward, as the“step and riser” architecture of the present invention assists thegrain's rearward travel.

In another embodiment of the present invention, the functions of sieveand chaffer are combined on the chaffer by means of two differentstructures: air jets and chaffing screens.

In another embodiment of the present invention, the air jets arelongitudinally constricted in cross section so as to increase the speedof air flow there through and thus increase the air blast created.

It is a further aspect of the present invention that screen hole sizeand shape may be selected without regard to a “filtering” function bythe screen, as such filtering occurs above the screen.

It is a further aspect of the present invention that the air jetopenings are not needed or used for grain separation.

In another embodiment of the present invention that the chaffer on thecombine may be changed on an element by element basis, rather than bychanging the entire chaffer.

In another embodiment of the present invention, the air jet openings andscreen hole openings may be of fixed size and configuration so as toeliminate the need for frustrating and error-prone adjustment of louverconfigurations of prior art systems.

It is a feature of the present invention that lower cost chaffers may bemanufactured which allow exacting standards for production and provideprecision operation.

It is another feature of the present invention that white caps may becaught with a high degree of efficiency without the need for precisionsifting.

It is a feature of the present invention that low cost chaffers which donot require any adjustment may be used, each chaffer being optimized toone grain type.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of the plenum of a combine showing indouble partial cross sectional view a high capacity air jet chafferaccording to a first embodiment of the present invention.

FIG. 2 is a three dimensional perspective view of a chaffer according toa second embodiment of the present invention.

FIG. 3 is a partial three dimensional perspective view of the secondembodiment of the chaffer.

FIG. 4 is a frame-removed side view of the chaffer, showing an elementof the chaffer positioned for removal or insertion, according to thesecond embodiment of the invention.

FIG. 5 is a partial three dimensional perspective view of the secondembodiment of the chaffer.

FIG. 6 is a side view of the second embodiment of the chaffer (chafferframe removed and element frame removed), showing the multiple air flowsthrough the chaffer and the structure of the chaffer element.

FIG. 7 is a partial top view of a third embodiment of the chaffer,partially showing one element thereof and further showing the retainersand the screen and holes of the element.

DETAILED DESCRIPTION OF THE DRAWINGS

The present invention teaches the use of at least one air jet dedicatedto the task of blowing chaff, white caps, crop heads, straw, dirt andother debris and having themselves no filtering function, interspersedwith screens which easily allow passage of grain of the correct size.The grains with which the present invention may be used include, but arenot limited to, wheat, millet, sunflowers, canola, milo, barley, oats,corn, popcorn, rye, beans, flax seed, sorghum, soybeans, dry ediblebeans, dried peas, food grains, feed grains, oil seeds, geneticallyaltered grains, rice, faba beans, radish seeds, and other crops ofvarious sizes. For example, canola seeds are typically two millimetersor less in size (very roughly {fraction (1/12)}th of an inch) while fababeans may average an inch or more in size. Radish seeds are evensmaller. This wide range is made possible by providing non-adjustablechaffers which may be easily replaced by one man and which are optimizedfor a given size of grain.

FIG. 1 is a cross sectional view of the plenum 62 of a combine showingin double partial cross sectional view high capacity air jet chaffer 10according to a first embodiment of the present invention. Chaffer 10,the invention, sits above sieve 58 of known type. Arrows 66 and 68indicate the reciprocation of chaffer 10 and sieve 58. Usually, chaffer10 and sieve 58 move in opposite directions. Arrow 56 indicates the airintake into cleaning fan 44 located in fan housing 46, while arrow 64indicates the airflow through plenum 62. Note that chaffer 10 shown in adouble partial cross sectional view: the first cross sectional viewillustrates the interspersed air jets and screens of the invention; thesecond cross sectional view illustrates the (known) rethresh louverswhich allow unthreshed materials to be taken back to the threshing stage(not shown) for rethresh and return to chaffer 10.

In operation, intake airflow 56 flows through cleaning fan 44 to enterplenum 62 as air flow 64. Air then flows through sieve 58 in a mannerknown in the art, then flows through chaffer 10 in a manner unique tothe invention.

Threshed grain and other materials cascade down onto chaffer 10 from thethreshing stage (not shown). Normally, this will be a continuous streamof grain, straw, chaff, dirt, unthreshed or partially threshed grainheads, and other materials, however, this stream may from time to timebe interrupted or may vary in volume depending on the crop density ofthe areas being harvested, in a manner which is sometimes unpredictable.The invention, chaffer 10, will blow the lighter and less densematerials backwards from that portion of chaffer 10 having jets andscreens. The lightest materials, chaff, straw, etc, will simply belofted entirely over the end of chaffer 10 and will depart the aft endof the combine. Those materials of intermediate weight such as partiallythreshed heads, unthreshed heads, white caps and the like will only belofted over the portions of chaffer 10 having air jets. The aft/rearwardsection of chaffer 10 having rethreshing louvers, however, will allowthese materials to fall through chaffer 10 to tailings auger trough 52,at which location tailings auger 54 will return them to the threshingstage (not shown) for rethreshing. Should any such materials manage topass chaffer 10, they will nonetheless be conveyed to auger trough 52 bysieve 58.

The heaviest/densest materials, however, will be the properly threshedgrain. This will fall through chaffer 10 and sieve 58, through plenum 62to clean grain auger trough 48. There, clean grain auger 50 will beginthe process of moving the clean grain to a storage bin (not shown)located atop the combine or in another vehicle paralleling the combine.

Tests have confirmed that the clean grain does not block chaffer 10 fromthe “bottom” side. Without wishing to be bound by any one theory, it isbelieved that the pressure in plenum 62, and thus the draft within (airflow 64) is slow enough that the grain's trajectory is not impacted andthe grain does not get sucked upwards from below into the air jets orapertures.

In this embodiment, chaffer 10 may be employed without the use of sieve58. This is possible because the cleaning efficiency and cleaningcapacity of chaffer 10 greatly exceeds that of previous chaffers.

FIG. 2 is a three dimensional perspective view of chaffer 10 accordingto a second embodiment of the present invention. This embodiment isinterchangeable with the first embodiment of the invention, except asnoted below.

In this embodiment, the chaffer is composed of a number of chaffingelements as exemplified by chaffing element 14. The chaffing elements ingeneral are “coterminous” in the sense that they are locatedsubstantially side by side with only small gaps or no gaps between theelements, the elements and the baffles, etc. Baffle 72 divides chaffer10 longitudinally between the elements. The purpose of baffle 72 is toprevent grain from sliding laterally across chaffer 10 when the combineis operating in a “sidehill” condition, i.e. on the side of a hill. Thelength and width of chaffer frame 12 may be entirely taken up bycombined element lengths and element widths of the chaffing elements,or, as in the presently preferred embodiment, there may be additionalfeatures within the chaffer frame 12, such as the rethreshing louvers.Chaffer frame 12 also defines chaffer length and chaffer width ofchaffer 10. Chaffing element 14 may be removed without removing theremainder of chaffer 10. While removal of chaffer 10 is a two person jobrequiring access to the interior of the combine from the back, removalof one chaffing element somewhat simplifies this task. Each element ismuch lighter and smaller, making the removal of ancillary equipment lessnecessary and rendering the task of altering chaffer 10 so much easierand quicker as to make it a one person job.

One motivation for known designs to teach chaffers and sieves havingadjustable louvers was the desire to avoid changing of the chaffers whengoing from crop to crop. However, by rendering the changing of chaffer10 easier, the present invention teaches that having specialty chaffersfor each crop is again possible. This ends the guesswork in chafferadjustment, in which louvers which are maladjusted either reducechaffing capacity or else blow grain onto the ground behind the combine.The reason that the changing of chaffer 10 is easier, of course, is thatframe 12 of chaffer 10 is not actually normally changed. Instead,individual ones of a plurality of coterminously positioned removablechaffing elements (such as element 14) are changed, a much easier task.

Element support rod 60 retains element 14 in place from the bottom, aswill be discussed further below.

FIG. 3 is a partial three dimensional perspective view of the secondembodiment of chaffer 10. As may be seen, the front end of chaffer 10,which is the end most deeply within the combine, has mounted uponchaffer frame 12 spring clip 16 which impels the front end of element 14downwards when element 14 is being removed or inserted. This greatlyassists the removal or insertion.

FIG. 3 also shows details of the air jet 22, riser 20, and chaffingscreen 18. Element 14 is generally formed in a “staircase” crosssection, that is a plurality of steps each having a riser portion and atread portion. The riser of each step of the “staircase” is riser 20,the tread of each step is chaffing screen 18. The risers each adjoin thescreens and in the preferred embodiment are substantially perpendicularthereto. Air jet 22 is located at a distance from the joint of screen 18and riser 20, whereby the air blast parallel to screen 18 is displacedfrom screen 18 by the same distance.

It will be remembered that in many combines, chaffer 10 will actuallyslope upwards towards the rear (as shown in FIG. 1), or be roughlyhorizontal, in addition to uses in which it slopes downwards towards therear, as shown in FIG. 3. A trough portion (that volume in the angle ofthe step below air jet 22 and running across the lower elevations ofscreen 18) is also present. The trough portion is caused by the factthat air jet 22 is positioned, in the preferred embodiment, at adistance above screen 18, by which means the air blast from airjet 22 isnot directed across the face of screen 18 but rather just above the faceof screen 18. This distance may be varied or eliminated in other lesspreferred embodiments of the invention.

The word screen, as used herein, is understood to mean a regular patternof apertures characterized by a relatively high percentage of surfacearea being aperture and a relatively low percentage of the surface areabeing support structure between apertures. Less generally, a screen forthese purposes will have a surface in which approximately 25% or more ofthe surface is aperture. Specifically, the screen should comprise anapertures of 40-90% of the surface area, most preferably, 60-80% of thesurface area. In particular a single line of holes which togethercomprise less than 10% of the surface area is obviously not a screen asthe term is used herein.

The important factors in determining the screen aperture size and thedensity or compactness of the apertures are the size of the grain andthe ability of the manufacturing facility to leave sufficient materialbetween the screen apertures for a sturdy construction and a durableproduct. The size of the screen itself is determined, as will beexplained below, by the “range” of the individual air jets, that is,their ability to blow materials from step to the next and thus into theair blast of the next air jet.

Features of the present invention are clearly illustrated by FIG. 3.First, as a plurality of air jets are dimensioned and configured toprovide the “air blast”, the air blast function is carried out by astructure which is entirely separate from the structure which carriesout the “sifting” “sieving” or “filtering” function, that is, aplurality of screens positioned between the air jets, i.e. chaffingscreen 18. Thus the air blast which is used to separate the grain fromthe chaff is NOT emitted by the plurality of apertures in chaffingscreen 18, and the plurality of apertures may be dimensioned andconfigured to admit such crop without other function, and thus arelatively easy passage for grain is allowed through screen 18. Inaddition, in the presently preferred embodiment and best mode presentlycontemplated for carrying out the invention, air jet 22 is in fact smallenough in the vertical dimension to prevent passage of grain.

A second feature of the present invention is well illustrated by FIG. 3.This is the fact that the air blast (not shown) is not parallel and/oropposed to the flow of grain through the apertures of screen 18, and isnot parallel to the sides of the apertures of screen 18, but rather isperpendicular to the flow of grain and is further perpendicular to theplurality of apertures of screen 18 and parallel to screen 18 itself.This configuration is made possible by the feature mentioned in thepreceding paragraph, that the air blast is generated by a structureseparate from the apertures of screen 18.

The air jet 22 used in the preferred embodiment is a “two dimensional”nozzle or “linear air jet” which stretches laterally, substantiallyacross the width of an individual chaffing element, for example, fromone side of element 14 to substantially the other side of element 14 asa substantially or wholly unbroken (continuous) nozzle. In otherembodiments, this configuration may be altered.

FIG. 4 is a frame-removed side view of chaffer 10, showing element 14positioned for removal or insertion, according to the second embodimentof the invention. Chaffing element 14 has element frame 26, not to beconfused with chaffer frame 12. Element frame 26 has alignment notch 28,dimensioned and configured so as to engage hinge pivot 24. In thepresently preferred embodiment, hinge pivot 24 is a bar or tubestretching laterally across the width of chaffer 10. During insertion ofelement 14 into chaffer 10, the front end of element frame 26 may berested on hinge pivot 24 and slid deeper into the combine until notch 28engages hinge pivot 24. The operator will immediately receive positivetactile feedback that element 14 is in the correct placement. Inaddition, the engagement of alignment notch 28 with hinge pivot 24 willhelp hold chaffing element 14 securely in place within frame 12 ofchaffer 10. Referring back to FIG. 3, it will be seen that the next stepin inserting chaffing element 14 into chaffer 10 is to raise the frontend of element 14 by lowering the rear end (not depicted in FIG. 3 orFIG. 4) until the front end of element 14 pushes spring clip 16 andseats itself there against. When element 14 is properly seated withinframe 12, spring clip 16 urges element 14 away from the frame. Note thatspring clip 16 may be many types of equivalent spring, or otherequivalent device, and need not only be a relatively flat spring clip.

Element support rod 60 (FIG. 2) and hinge pivot 24 will both act toretain element 14 within frame 12. Note that element support rod 60 andhinge pivot 24 are structurally both rods running across the width ofchaffer 10, however, hinge pivot 24 is used to align element 14 androtate it into place.

FIG. 5 is a partial three dimensional perspective view of the secondembodiment of chaffer 10. As may be seen, the rear end of chaffingelement 14 has hold down flange 34 have hole 36 there through. Thesecond step in insertion of chaffing element 14 into chaffer 10, raisingthe front end and lowering the rear end, causes hole 36 to pass overhold down bolt 32. Hold down bolt 32 is set into a cross member of frame12.

As will be readily apparent, spring clip 16 holds the front end ofelement 14 down, hinge pivot 24 and element support rod 60 hold theelement up, and flange 34 will hold the rear end of element 14 up. Thus,element 14 is held in place securely, yet is easy to remove and replace,and furthermore is automatically guided into the proper position.

Another feature of the second embodiment of chaffer 10 may be seen byreference to FIG. 5. Rethresh louver 30 is a louver such as known in theart, which allows materials too large to pass screen 18 to fall throughthe rearmost section of chaffer 10. This material, white caps and otherunhusked or unthreshed material containing grain is, as discussed withreference to FIG. 1, taken by tailings auger 54 back to the threshingstage (not shown) for rethreshing, after which, it is again sent overchaffer 10 for chaffing.

Although not shown, chaff and other loose, light materials will simplybe blown upwards and backwards away from high capacity air jet chaffer10 and thence out of the rear end of the combine, possibly assisted byother devices known in the art.

FIG. 6 is a side view of the second embodiment of chaffer 10 (withchaffer frame 12 removed and element frame 26 removed), showing themultiple air flows through chaffer 10 and the cross sectional structureof chaffer element 14. Screen 18, riser 20 and jet 22 all influence theflow of air through element 14. Arrows 40 indicate the air flow due toback pressure in plenum 62 (not shown), this flow is generally of lowspeed, as the substantial open areas of screen 18 (as suggested earlier,25% or more of the surface area is preferable, 40-90% more preferable,and 60-80% most preferable) do not allow a build up of great backpressure.

Arrows 42 indicate the air flow due to fan 44 (FIG. 1). Air jet 22 isapproximately parallel to air flow 42 even before air flow 42 passesthrough air jet 22. Note that this is not a requirement of theinvention: air jet 22 may be positioned at a substantial angle to airflow 42 and yet still be dimensioned and configured so as to provide asatisfactory air blast, however in the preferred embodiment and bestmode presently contemplated for carrying out the invention, the anglebetween air flow 42 and air jet 22 is not large.

As used herein, the word “jet” is used to mean more than a simple gap orlouvered opening. Louvers, as commonly used in the prior art, areparallel plates which simply redirect an air flow through the gapbetween without otherwise altering it. A “jet” as used herein, however,utilizes both the forced draft from a fan (such as fan 44) and also thepressure difference between inlet and outlet to generate an air blastwhich is more powerful (in the path of the blast downstream) than theair flow into the jet on the upstream side. Reference to FIG. 6 showsthat the area of riser 20 is substantially greater than the area ofairjet 22. This assists air jet 22 in developing a more powerful airblast. In addition, in the embodiment pictured, air jet 22 narrows frombase to outlet, thus causing an increase in air velocity from thenozzle. Thus, the proportionate difference in area between the nozzleand the base of air jet 22 is added to the proportionate difference inarea between the nozzle and riser 20, and further is added to the airspeed already present due to the effects of fan 44 (FIG. 1) and theresult is an air blast across the face of screen 18 which relativelyvery strong in comparison to the air flow through screen 18. Inparticular, in the presently preferred embodiment of the invention, theangle of exhaust of the plurality of air jets approximates the angle ofair flow from such fan. In other embodiments (not pictured) the air jetmay have parallel walls from base to outlet, or even may widen. Suchalternative embodiments may offer advantages in terms of staying clearand unclogged. In other embodiments, the air jets may be positioned tohave an angle of exhaust substantially different from that of the fan,or have other air moving structure than the fan by which means the jetsdevelop the air blast.

As previously mentioned in the preferred embodiment air jet 22 isdimensioned and configured so as to be too small to allow entrance ofgrain there through, however, this entrance may be prevented by othermeans. In the preferred embodiment, the air blast from air jet 22 isalso too powerful to admit grain. Other structure may be used, forexample, physical bars to entry. As previously mentioned, for wheat, theair jet of the preferred embodiment is presently manufactured to have agap of {fraction (3/16)} inch. The width of the air jet may be of otherdimensions, however, as long as it is dimensioned and configured tosubstantially alter the trajectory of the chaff, straw, stems and otherlight weight MOG falling into its air blast. In addition to grain sizeand desired power, the width of the air jet may be varied so as to avoidclogging of the air jet by grain, chaff, dirt and other materials.

Air jet 22 may also be positioned elsewhere than shown by FIG. 6. Forexample, air jet 22 may be positioned further up the side of riser 20.In this event, the separation of the air blast generated by airjet 22and the mat of material atop screen 18 is increased. Airjet 22 may alsobe positioned lower down on riser 20. This may be useful in applicationsdesigned for crops of differing sizes, or may be implemented for otherreasons.

For purposes of this application, an “air blast” is thus any air flowwhich is powerful enough to substantially alter the trajectory ofrelatively low density materials falling through it. In the preferredembodiment, the air blast is in fact powerful enough to prevent theentrance of grain into the air jet. Normally, such air blasts will beforced by a fan (or conceivably induced by a fan) and/or by an air jet.This is by contrast to the relatively weak airflow which may beexperienced through the plurality of apertures of a screen. A screenhaving a plurality of apertures covering a substantial portion of thesurface area of the screen relatively weak flows are caused by backpressure inside a plenum such as plenum 62. Such a relatively minimalairflow will not impede the passage through an aperture of grain. In thepresent invention, the term “minimal” airflow includes no airflow at allthrough the apertures.

Another feature of the present invention is illustrated by FIG. 6. Incontrast to prior art chaffers in which the largest apertures throughwhich grain can fall are the louvers themselves (such as the '059patent) or in which the louvers themselves are the only apertures thoughwhich the grain can fall (the '574 patent and other references cited),and thus the air blast cannot be powerful enough to entirely shield theapertures, in the present invention, the air blast shields the onlyapertures which accept grain by virtue of forcing itself across the faceof the apertures perpendicular to the fall of the grain. Thus, a morepowerful air blast is permissible without preventing the apertures ofthe chaffer from allowing the grain passage. The lower density chaff ismore susceptible to being blown off of a falling trajectory than thegrain, and when so blown, it is likely to cross from one step to thenext and be caught by a second air blast, and by this means eventuallyreach the end of the chaffer. In the presently preferred embodiment, thedistance between two risers (also equivalent to the length of eachscreen) is roughly 3 to 4 inches. This may be thought of as being the“range” of the airjet, and the screens may be made a length which allowsthe combined airjets in series to maintain an acceptable air velocityacross the length of chaffer 10. The length of the screen is thusrelated to the range of the airjet in any given condition.

The reciprocating/vibratory motions of chaffer 10 further causes riser20 to push against whatever grain may be lying atop screen 18, sendingany such grain upwards across screen 18 and providing it with furtherchances to achieve the correct orientation to fall there through.

While the structure disclosed in the preferred embodiment relies uponjets which are at a modest angle to the air flow from the fan and screenapertures which are perpendicular thereto, other equivalent ways ofgenerating a strong air blast from a source other than the screenapertures will be readily apparent to those skilled in the art afterreading this disclosure. And while the best mode presently contemplatedrelies upon air blasts which are substantially perpendicular to thescreen apertures (and parallel to the screen faces) other equivalentangular arrangements may also fall within the scope of the appendedclaims.

A practical feature of the invention which is also depicted in FIG. 6 isgap 70 between flame 12 and element 14 seen below spring clip 16. Sinceunlike prior art chaffers, element 14 may be removed and replaced fromtime to time, there must be gap 70 to allow element 14 to swing out whenbeing removed and replaced. Gap 70 is small enough to prevent grainentry or passage there through. In some prior art chaffers which sit onrails or tracks, the gap all around the prior art chaffer fills withdirt and chaff and prevents the chaffer from seating properly unless therail or track is thoroughly cleaned at the time of changing chaffers. Inthe present invention, the only location at which dirt or chaff canaccumulate is the extreme rear of the chaffing element, under flange 34.That location, however, is easily accessible to the operator.

FIG. 7 is a partial top view of a third embodiment of chaffer 10,partially showing one element thereof and further showing retainer 38and details of screen 18.

At the rearward end of element 14, hold down flange 34 has hole 36 (seeFIG. 5) which fits over hold down bolt 32. Retainer 38 is then placed onhold down bolt 32 to secure element 14 in place against the resistanceof spring clip 16. Once in place, element 14 is held by spring clip 16at the front end, hinge pivot 24 and element support rod 60 in themiddle, and retainer 38 at the rear end. Thus element 14 is sandwichedinto frame 12 so as to avoid vibration. Spring clip 16 also helpscompensate for wear or warp to avoid rattle.

While the drawings depict a bolt and a wing nut, many other equivalentretainers may be used for this function which will accomplish the sameresult in the same way.

Details of screen 18 are also visible in FIG. 7. As shown, screen 18 hasa regular pattern of hexagonal holes. However, the holes may be round,square, polygonal, irregular or other shapes as appropriate for thegrain for which the chaffing element 14 is optimized. The size of theholes may also vary depending upon the grain, as may details of theconstruction of the screen such as thickness, material, hole pattern,and so on. The surface area of the screen should be substantially takenup by the apertures/holes, so as to allow grain flow there through atthe highest possible rate. Thus many other equivalent screens may beused for this function which will accomplish the same result in the sameway.

The invention does not rely on critical openings to achieve satisfactoryseparation of fully threshed and unthreshed grain and material otherthan grain. Screen hole size and shape is selected to be slightly largerthan the largest grain in any particular crop. Material other thangrain, such as chaff and straw, is less dense than grain and is blownrearward by the high velocity air streaming from the air jets and isthereafter discharged out the back of the combine. Since the air jetsopenings are not needed nor used for grain separation, the opening isfixed and relatively narrow. This eliminates the frustrating job ofprecise settings of adjustable louvered or air foil designs which alsointeracts with and effects the air flow.

In view of the fact that the grain is essentially cleaned beforereaching screen 18, and the fact that screen 18 may be properly sized atthe time of manufacture without need for operator adjustment, the highcapacity air jet chaffer diminishes the need to rely on the sievelocated lower down in plenum 62 for thorough cleaning of the grain. Infact the sieve can be removed or set wide open with no degradation ingrain quality. As a practical matter, using a sieve restricts the flowof air needed by the chaffer, thus operators may advantageously removesieves even from combines which have two or more levels of chaffing,thus increasing the efficiency of airflow and chaffing capacity, anddoing so without losing any efficiency in the cleaning process.

In the embodiment depicted, the invention is optimized for wheat, andthus the holes in the screen are {fraction (1/4)} inch hexal holes whilethe nozzle width is {fraction (3/16)} inch. However, if the device wereto be optimized for use with faba beans, for example, the nozzle widthmay be {fraction (1/2)} inch and the apertures 1 inch across. Werecanola to desired crop, the aperture size may be {fraction (1/8)} inch.

Any grain that is still unthreshed from the seed head of the plant,attached to the cob, or in the pod; remains too large to pass throughthe screen holes and is advanced rearward (due to being pushed by therisers) until reaching the louvered section above the tailingscollection system. These unthreshed heads, cobs, or pods pass throughthe louvers into the tailing system and are returned to the thresher foradditional threshing until fully threshed.

This disclosure is provided to allow practice of the invention by thoseskilled in the art without undue experimentation, including the bestmode presently contemplated and the presently preferred embodiment.Nothing in this disclosure is to be taken to limit the scope of theinvention, which is susceptible to numerous alterations, equivalents andsubstitutions without departing from the scope and spirit of theinvention. The scope of the invention is to be understood from theappended claims.

1. A combine crop chaffer comprising: a chaffer frame having a lengthand a width, and a plurality of coterminously positioned removablechaffing elements disposed within the chaffer frame.
 2. The chaffer ofclaim 1, wherein the chaffer frame further comprises: a hinge pivot; andfurther wherein at least one of said chaffing elements further comprisesan element frame, the element frame having an alignment notch therein,the alignment notch being dimensioned and configured to engage the hingepivot when the chaffing element is properly positioned within thechaffer frame and further dimensioned and configured to allow thechaffing element to then be rotated until it is properly oriented withinthe chaffer frame.
 3. The chaffer of claim 2, further comprising: aspring located upon the chaffer frame, the spring dimensioned andconfigured to engage the front end of at least one the plurality ofchaffing elements when the chaffing element is properly seated withinthe chaffer frame, and the spring further urging the front end of theengaged chaffing element to rotate away from its seated position withinthe chaffer frame.